log exceptions when processing delegation metadata
log exceptions when processing delegation metadata

findTargetInDelegationTree() has a number of possibly thrown exceptions:
- SecurityException("image", "Rollback attempt on delegated targets")
- Uptane::Exception("image", "Inconsistent delegations")
- Uptane::DelegationMissing
- Uptane::DelegationHashMismatch
- VersionMismatch

Log the exceptions when caught

Signed-off-by: Benjamin Clouser <318d09978a11718ac0de401c132f6956c6cd168d@toradex.com>

advancedtelematic/aktualizr,advancedtelematic/aktualizr,advancedtelematic/aktualizr,advancedtelematic/aktualizr